PRO BASKETBALL; Erving Still Searching for Son

Julius Erving returned to the city of his greatest basketball success today to plead again for help in finding his missing son.

The National Basketball Association great said he thinks that 19-year-old Cory Erving is still alive, and might have been using drugs at the time of his disappearance in late May. Cory has had a history of drug and alcohol abuse as well as run-ins with the law. ''I don't think he was clean,'' Erving said today on ABC's ''Good Morning America.'' ''I think he was still participating.''

Erving, an executive with the Orlando Magic, appeared at City Hall with his other sons, 26-year-old Julius III and 27-year-old Cheo. Both choked back tears as they described their brother as a fun-loving prankster and pleaded with him to come home.

Erving's disclosure of his son's disappearance on June 13 produced hundreds of tips, including 34 from the Philadelphia area. But the deputy police commissioner, Sylvester Johnson, said today that none of them panned out. There is ''nothing substantial to say that he's here,'' Johnson said, although Cory has friends in the area and Julius III runs a sports and entertainment marketing business here.

Mayor John F. Street, who has known Erving for many years, pledged the resources of the police department to ''help get this situation resolved.''

Despite nearly two weeks of national media exposure, there has been no sign of Cory or his black 1999 Volkswagen Passat.